Hello Nickoli,
The new Intel cores run about 25$ more total throughput while hyperthreading.But the problem is that you only have 2GB which has to run the OS as well. If you are not running CEP2, just FAAH, you might try 75% or even 100%. If you had 3 or 4 GB, you could do best at 100% but with your memory you might be at the optimum. You could try experimenting while checking memory usage, speed, etc.

Lawrence

It will make WU run longer but that's not the point. In many situations HT will increase your overall points per hour even though the units have longer run times.

What Lawrence suggested is the only way you can be certain if HT is the best answer for your particular system and circumstances. Run at 50% on a single science for a set period of time, say a week, then do the same test at 100% (or whatever percentage) and compare the long-term averages. Anything less will be too susceptible to statistical flukes and will not give you a true answer.